Diatomaceous earth products are obtained from diatomaceous earth (also called “DE” or “diatomite”), which is generally known as a sediment enriched in biogenic silica (i.e., silica produced or brought about by living organisms) in the form of siliceous skeletons (frustules) of diatoms. Diatoms are a diverse array of microscopic, single-celled, golden-brown algae generally of the class Bacillariophyceae that possess an ornate siliceous skeleton of varied and intricate structures comprising two valves that, in the living diatom, fit together much like a pill box.
In the field of filtration, methods of particle separation from fluids may employ diatomaceous earth products as filter aids. The intricate and porous structure unique to diatomaceous earth may, in some instances, be effective for the physical entrapment of particles in filtration processes. It is known to employ diatomaceous earth products to improve the clarity of fluids that exhibit turbidity or contain suspended particles or particulate matter.
Diatomaceous earth may be used in various embodiments of filtration. As a part of pre-coating, diatomaceous earth products may be applied to a filter septum to assist in achieving, for example, any one or more of: protection of the septum, improvement in clarity, and expediting filter cake removal. As a part of body feeding, diatomaceous earth may be added directly to a fluid being filtered to assist in achieving, for example, either or both of: increases flow rate and extensions of the filtration cycle. Depending on the requirements of the specific separation process, diatomaceous earth may be used in multiple stages or embodiments including, but not limited to, in pre-coating and in body feeding.
Diatomaceous earth products are generally made by processing very finely divided diatomaceous earth, including the diatomaceous earth ore. For example, in order to obtain a product suitable for use as a filter aid, finely divided diatomaceous earth may be granulated in an agglomeration process. One suitable agglomeration process is described in US 2010/0248593.